You are not alone. . . we thought our son (9) would be pleased that mom and dad were closer and acting as a unit. Not so! He was angry at first when the boundaries shifted, and he felt very left out. He said we were on a "love canoe" and he felt like there was no room for him there. We did have a very child-centered family life, which turned out to be kind of a problem.
I am not sure we have hit the correct balance yet - I worry that we are putting a lot into us now, and not enough into him. (Babysitters once a week, too much "TV time" while we hash stuff out.
It is true, though, that I got a lot of needs for affection and just being needed from my son -- and I have to believe that in the end, shifting some of this away from him is healthier for all of us. Also, I know that my H and I being securely attached is much, much better for him.
It has been 4 months for us, and our son is adjusting, and he does seem happier. We are all happier as a family, so have hope. You can talk with her about how you guys realized that in order to have a happy marriage, you needed to pay more attention to each other. Since you are teaching her what she'll emulate one day, it is a good message.